Russo/Booker T in a steel cage for the WCW World Heavyweight Championship or Arquette/DDP vs. Bischoff/Jarrett (whoever got the pin became the WCW World Heavyweight Champion) or Arquette/Page/Jarrett in a Triple Cage Match for the WCW World Heavyweight Championship
Oh, wait....you said "best"....my bad.
Serious Answers:
Sting vs. Cactus or Sting vs. Flair (there's a reason the last match ever on Nitro was Sting vs. Flair)
I'll second Flair/Steamboat, Cactus/Vader, Sting/Vader, Malenko/He-Who-Must-Not-Be-Named, Eddie/Rey, anything involving Chris Jericho.
WCW really had some great in-ring performers for a long time. At a certain point, though, they forgot what the show is about.
wk